21221110121 has 8 divisors (see below), whose sum is σ = 21322802760. Its totient is φ = 21119617152.

The previous prime is 21221110067. The next prime is 21221110187. The reversal of 21221110121 is 12101112212.

It can be written as a sum of positive squares in 4 ways, for example, as 8342264896 + 12878845225 = 91336^2 + 113485^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221110121 - 2¹⁰ = 21221109097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221110096 and 21221110105.

It is not an unprimeable number, because it can be changed into a prime (21221110321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165365 + ... + 264173.

It is an arithmetic number, because the mean of its divisors is an integer number (2665350345).

Almost surely, 2^21221110121 is an apocalyptic number.

It is an amenable number.

21221110121 is a deficient number, since it is larger than the sum of its proper divisors (101692639).

21221110121 is an equidigital number, since it uses as much as digits as its factorization.

21221110121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99835.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21221110121 its reverse (12101112212), we get a palindrome (33322222333).

The spelling of 21221110121 in words is "twenty-one billion, two hundred twenty-one million, one hundred ten thousand, one hundred twenty-one".